28,220 research outputs found
Electromagnetic prompt response in an elastic wave cavity
A rapid, or prompt response, of an electromagnetic nature, is found in an
elastic wave scattering experiment. The experiment is performed with torsional
elastic waves in a quasi-one-dimensional cavity with one port, formed by a
notch grooved at a certain distance from the free end of a beam. The stationary
patterns are diminished using a passive vibration isolation system at the other
end of the beam. The measurement of the resonances is performed with
non-contact electromagnetic-acoustic transducers outside the cavity. In the
Argand plane, each resonance describes a circle over a base impedance curve
which comes from the electromagnetic components of the equipment. A model,
based on a variation of Poisson's kernel is developed. Excellent agreement
between theory and experiment is obtained.Comment: 4 pages, 5 figure
Scattering of Elastic Waves in a Quasi-one-dimensional Cavity: Theory and Experiment
We study the scattering of torsional waves through a quasi-one-dimensional
cavity both, from the experimental and theoretical points of view. The
experiment consists of an elastic rod with square cross section. In order to
form a cavity, a notch at a certain distance of one end of the rod was grooved.
To absorb the waves, at the other side of the rod, a wedge, covered by an
absorbing foam, was machined. In the theoretical description, the scattering
matrix S of the torsional waves was obtained. The distribution of S is given by
Poisson's kernel. The theoretical predictions show an excellent agreement with
the experimental results. This experiment corresponds, in quantum mechanics, to
the scattering by a delta potential, in one dimension, located at a certain
distance from an impenetrable wall
The solar siblings in the Gaia era
We perform realistic simulations of the Sun's birth cluster in order to
predict the current distribution of solar siblings in the Galaxy. We study the
possibility of finding the solar siblings in the Gaia catalogue by using only
positional and kinematic information. We find that the number of solar siblings
predicted to be observed by Gaia will be around 100 in the most optimistic
case, and that a phase space only search in the Gaia catalogue will be
extremely difficult. It is therefore mandatory to combine the chemical tagging
technique with phase space selection criteria in order to have any hope of
finding the solar siblings.Comment: To be published in the proceedings of the GREAT-ITN conference "The
Milky Way Unravelled by Gaia: GREAT Science from the Gaia Data Releases", 1-5
December 2014, University of Barcelona, Spain, EAS Publications Series, eds
Nicholas Walton, Francesca Figueras, and Caroline Soubira
Cellular automaton supercolliders
Gliders in one-dimensional cellular automata are compact groups of
non-quiescent and non-ether patterns (ether represents a periodic background)
translating along automaton lattice. They are cellular-automaton analogous of
localizations or quasi-local collective excitations travelling in a spatially
extended non-linear medium. They can be considered as binary strings or symbols
travelling along a one-dimensional ring, interacting with each other and
changing their states, or symbolic values, as a result of interactions. We
analyse what types of interaction occur between gliders travelling on a
cellular automaton `cyclotron' and build a catalog of the most common
reactions. We demonstrate that collisions between gliders emulate the basic
types of interaction that occur between localizations in non-linear media:
fusion, elastic collision, and soliton-like collision. Computational outcomes
of a swarm of gliders circling on a one-dimensional torus are analysed via
implementation of cyclic tag systems
Absorption and Direct Processes in Chaotic Wave Scattering
Recent results on the scattering of waves by chaotic systems with losses and
direct processes are discussed. We start by showing the results without direct
processes nor absorption. We then discuss systems with direct processes and
lossy systems separately. Finally the discussion of systems with both direct
processes and loses is given. We will see how the regimes of strong and weak
absorption are modified by the presence of the direct processes.Comment: 8 pages, 4 figures, Condensed Matter Physics (IV Mexican Meeting on
Mathematical and Experimental Physics), Edited by M. Martinez-Mares and J. A.
Moreno-Raz
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